Spectrophotometric Standards

Select the IFU you what to use from the drop-down. Start with the closest one

Enter the standard star position and name (the name is used for the headers).

Press “Calculate”.

Work through the “Operations” at the bottom of the window.

Slew to star

Apply “Field Center to Guide Bundle offset”

Wait that night assistant center on the guide bundle.

Apply “Guide bundle to IFU offset”

“Run the observing script.” The script will prompt for an exposure time.

[If offset do not work, do offset by hand – night assistant – and re-run the script]

The script will take three flux calibration exposures (with offsets of 2.5 arc-seconds). It will then take a FLAT and an ARC using standard exposure times in the script (80 seconds and 10 seconds) including moving the dome windscreen to the correct position and turning on/off the lamps.

You then need to observe the standard through a second hexabundle. To do so you can remove the IFU to Guide offset and then select a new IFU and repeat the above procedure.

If for some reason the default 10 and 80s exposure times for the arc and flat are not giving the correct counts, then these can be changed by editing the script, but do not edit any other part of the script apart from the ftime and atime values for flat and arc respectively in